1. Field of the Invention
This invention relates to devices able to purify fluids electrically and, more particularly, to such devices contained within pressure vessels, as well as to methods of manufacture and use thereof.
2. Description of the Related Art
Devices able to purify fluids using electrical fields are commonly used to treat water and other liquids containing dissolved ionic species. Two types of devices are electrodialysis devices and electrodeionization devices. Within these devices are concentrating and diluting compartments, separated by anion and cation selective membranes. An applied electric field causes dissolved ions to migrate through the membranes, resulting in the liquid of the diluting compartment being depleted of ions while the liquid in the concentrating compartment is enriched with the transferred ions. Typically, the liquid in the diluting compartment is desired (the “product” liquid), while the liquid in the concentrating compartment is discarded (the “reject” liquid). In electrodeionization, the diluting and concentration compartments may also contain ion exchange resins. The ion exchange resin may act as a path for ion transfer, and also may serve as an increased conductivity bridge between the membranes for movement of ions.
Electrodeionization devices include “plate-and-frame” electrodeionization devices such as those disclosed by, for example, in U.S. Pat. No. 4,931,160 by Giuffrida, in U.S. Pat. No. 4,956,071 by Giuffrida et al., and in U.S. Pat. No. 5,316,637 by Ganzi et al. Electrodeionization devices having other geometries have been disclosed by, for example, in U.S. Pat. No. 5,292,422 by Liang et al., in U.S. Pat. No. 5,376,253 by Rychen et al., and in U.S. Pat. No. 6,190,528 by Li et al.